Add support for dai.ly urls in MediaEmbedEditing

[Kocal]

Suggested merge commit message (convention)

Feature: Add support for short Dailymotion URLs (dai.ly) in media-embed.

---

Additional information

Short Dailymotion URLs can be found in you share the video through the dedicated sharing button:

Example: https://www.dailymotion.com/video/x8ks8y1

[Witoso]

I'm not sure if we want to add more providers to the plugin except the most popular, as it's adds the maintenance cost. @Reinmar, thoughts?

[Kocal]

I can understand, but I didn't find anything in the documentation, like extending an existing media provider to add more URLs

[Witoso]

There's extending, removing, overriding. I am not sure if I understand your case.

[Kocal]

It's more something like extending a given mediaProvider to add another supported URL.

By doing something like:

{ 
  mediaEmbed: {
    extraProviders: [
      { 
        name: 'dailymotion',
        url: [/^dai.ly\/(\w+)/],
      }
    ]
  }
}

I was expecting my dailymotion configuration to be merged with the one from the MediaEmbed plugin itself, so maintaining would be easier/safer in our end-user side:

But it didn't work as I thought, I had to duplicate the dailymotion configuration from the MediaEmbed plugin, and add it like this:

{ 
  mediaEmbed: {
    extraProviders: [
      { 
        name: 'dailymotion',
        url: [/^dai.ly\/(\w+)/],
        html: (match) => {
          const id = match[1];
          return (
            '<div style="position: relative; padding-bottom: 100%; height: 0; ">' +
            `<iframe src="https://www.dailymotion.com/embed/video/${id}" ` +
            'style="position: absolute; width: 100%; height: 100%; top: 0; left: 0;" ' +
            'frameborder="0" width="480" height="270" allowfullscreen allow="autoplay">' +
            '</iframe>' +
            '</div>'
          );
        },
      }
    ]
  }
}

[Witoso]

Ok, gotcha. I forgot we actually had dailymotion 🤦  @arkflpc could you take a look and merge it?